This invention relates generally to transmissive screens, and more particularly to transmissive screens suitable for use in rear projection systems.
Rear projection screens are generally designed to transmit an image projected onto the rear of the screen into a viewing space. The viewing space of the projection system may be relatively large (e.g., rear projection televisions), or relatively small (e.g., rear projection data monitors). The performance of a rear projection screen can be described in terms of various characteristics of the screen. Typical screen characteristics used to describe a screen's performance include gain, viewing angle, resolution, contrast, the presence of undesirable artifacts such as color and speckle, and the like. It is generally desirable to have a rear projection screen that has high resolution, high contrast and a large gain. It is also desirable that the screen spread the light over a large viewing space. Unfortunately, as described more fully below, as one screen characteristic is improved, one or more other screen characteristics often degrade. For example, in order to increase the screen gain using the same overall structure, one must decrease the viewing angle over which the screen is readily observable. As a result, certain tradeoffs are made in screen characteristics and performance in order to produce a screen that has overall acceptable performance for the particular rear projection display application.
Rear projection display applications requiring high resolution are becoming more prominent. For example, high definition and digital television formats have relatively high resolution requirements. As a result, screens used in such rear projection televisions must be able to resolve the higher resolution images. Rear projection desktop data monitors also have high resolution requirements. As typical rear projection screens are modified to accommodate the higher resolution, the above-described tradeoffs tend to degrade other performance characteristics of the screen. Thus, there remains a need for screens that have improved the overall performance while meeting the minimum performance criteria necessary for the rear projection display application in which the screen is used.